OK, what type of fire would an arty unit use in this scenario.
An infantry squad sees a logistics unit (light skinned vehicles), moving in a 3 column formation, 50 meters between vehicles. How would the arty bn fire on these vehciles? I don't know the types of firing methods, other than hearing the term rolling barrage. Do all arty pieces fire at one point, or fire 50 meters apart in a line, then moving the aimed area forward???

Ok I'll take the bait.
First it would be best to get the colum to stop. So either squads finds out where thay are setting up the depo, or takes a fev potshots at the colun to make it stop.
A "logistics unit" might be a rather large concentration so I assume quite a few trucks etc.
there is really two ways to do it. use rocets against area target which is pectacular and doesn't take long or use few guns and take time and pinpoint the targets and take the aout one at the time.
I'd prefer areatarget quick volley with rockets and preferably white phosphorus and Napalm. (clothing items and foodstuff) dont really go spoiled as few grams of metal travel thorough them at velocities. well liquids tend to run dry put you get the picture. But if you trying to stop say armored columns you want them maintainance people gone and the the shrapnell comes really handy.

Get on the radio give length,depth and directionand rate of movement of convoy, center target grid.
FDC will figure a DPICM mission. A battery one, DPICM covers a 200 x 400 meter area.
Thats the easy way.